body {
    transition: all .5s;
}

@media (min-width: 768px) {
    .register {
        width: 50%;
    }
}

.nav-item {
    cursor: pointer;
}

.card-user-img img {
    width: 100%;
}

/* 返回顶部 */
#backToTop {
    display: none;
    position: fixed;
    bottom: 5%;
    right: 5%;
    z-index: 99;
    border: none;
    outline: none;
    background-color: #555;
    color: white;
    cursor: pointer;
    padding: 8px;
    border-radius: 4px;
}

#backToTop:hover {
    background-color: #444;
}